1. Field of the Invention
The present invention relates to a method for counting the number of passing persons by stature and more particularly to a method for counting the number of persons by stature who are passing through a gateway or a passage in a building such as a department store or an exhibition building.
2. Description of the Prior Art
Heretofore, there has been known a method for counting the number of passing persons wherein a projector and a receptor are disposed at an upper portion of a gateway or a passage. According to this method, when a person has arrived at a crossing portion of a light beam emitted from the projector and an extension of a light incoming path in the receptor, there is formed a light loop between the projector and the receptor. This light loop is then taken out as a signal and, thereafter, a counting operation is performed (as disclosed in Japanese Patent Laid-Open Nos. 65075/79 and 16278/80).
According to the above conventional method, it is possible to discriminate whether the stature of the passing person is large or small, that is, whether the passing person is an adult or a child, or whether baggage is passing through the gateway or passage, on the basis of the height of the loop formed. However, one set of the projector and the receptor merely permits the discrimination of the height, and it is impossible to discriminate plural heights, or count the number of passing persons by stature.
For the discrimination of plural heights in the conventional method it is necessary to provide several projectors according to the number of heights to be discriminated, resulting in that the mounting space becomes larger and a signal control means becomes complicated and expensive inevitably. Furthermore, for every change in position of the projector and the receptor it is required to manually adjust the respective positions. Since this adjustment is performed in high positions, not only the working efficiency is poor but also it is dangerous.